Do adults use "Pssst", too?

What is different between "come to visit" and just "visit"?

"Come to visit" means "arrived to visit". The narrator is saying that they have arrived with the intention of visiting Pedro, but they are not visiting Pedro yet. If the script was "Peppa and her friends visit Pedro", that would mean that they are currently doing the action of visiting Pedro.

What does "your forever" mean? Can "forever" be used as a noun?

In answer to the first question "your forever" here means your future. He is asking if when she imagines of any time in the future is he included in it. In answer to your second question "forever" can be used as a noun. As a noun, it means either an extremely long time if a mythical time in the future that may never come. Ex: It takes forever to set up a business. Ex: It took her forever to find the answer.

What's "Gold Rush?" Is this a famous historical period?

That's right! The "Gold Rush" is a famous historical period. It's when gold was found in California in 1848, and then 300,000 people went to California to look for more gold! They "rushed" over. Ex: A lot of people found gold nuggets during the Gold Rush. Ex: The Gold Rush ended in 1855.

What does "take a step back" mean?

"Take a step back" here refers to withdrawing from a situation and becoming less involved in it. She is saying that she thought once he was in high school, he would be more independent and she wouldn't have to tell him what to do as much, but that is not the case.

What does "beefcakes" mean?

"Beefcake" is an informal term for an attractive man with well-built muscles. It can also be used ironically or sarcastically. Ex: I swear, all these reality-dating shows just recruit as many beefcakes as they can. Ex: I mean, I'm no beefcake, but I still think she'd like me.